Question

The energy equation which is in terms of total energy can be changed to terms of internal energy using ___________

(a) momentum equation

(b) stress-strain relations

(c) equations of state

(d) continuity equation

This question was addressed to me during an interview.

The doubt is from Energy Equation topic in portion Governing Equations of Fluid Dynamics of Computational Fluid Dynamics

Answer 1

Correct choice is (a) momentum equation

To explain I would say: Total energy is the sum of internal energy and kinetic energy. By some manipulation in the momentum equation, we can get the kinetic energy terms. If this is subtracted from the energy equation written in total energy terms, we can get the same in terms of internal energy.